Conventional sewing machines have been provided with alerting devices that allow displaying of alert messages for prompting a user to refill or replace lubricant when cumulative sew time has exceeded a predetermined time period. One of such example is disclosed in JP 2006-263268 A (hereinafter referred to as reference 1). Reference 1, discloses a maintenance timing alerter that stores reference maintenance information. The reference maintenance information provides exemplary standard maintenance timing under exemplary standard load to provide a reference to the user as to when lubricant should be supplied to mechanical elements such as sliding engagement elements of a sewing machine operated under the exemplary standard load. The maintenance timing alerter monitors the actual load or conditions under which the sewing machine is being operated and corrects the standard maintenance timing based on the actual load to obtain a modified maintenance timing. Then, the maintenance timing alerter issues a warning to prompt lubricant refill to the user whenever cumulative sew time reaches the modified maintenance timing.
However, since the warning is only displayed once, the user may not notice the alert and allow the lubricant to run out, which in turn may cause seizures at the mechanical elements of the sewing machine such as the sliding engagement elements.